Risotto figures out that Doppio must be a Stand user that the boss trusts in deeply because he’s able to hear the noise from a certain Stand. Risotto then uses his Stand Metallic against him. Metallic is able to control magnetic force and attacks Doppio. Doppio uses the part of the boss’s power he received from him. While they’re fighting, Risotto realizes that Doppio’s personality and actions seem to be changing and he realizes exactly who Doppio is.
To put it simply, your blood turns a 
horrible shade of yellow and you die.
ببسيطِ العبارة، يصفرُّ لون دمك بشكلٍ
فظيع وثمّ تموت
Kurz gesagt: Dein Blut wird
ekelhaft gelb und du krepierst.
Tu sangre adquiere
un feo tono amarillento y mueres.
Tu sangre adquiere
un feo tono amarillento y mueres.
En gros, tu mourras lorsque ton sang
se teintera d’un jaune répugnant.
Per farla breve, il sangue assume un orribile
colore giallastro e la persona muore.
Basicamente, seu sangue vira um
soro amarelo e você morre.
Если кратко, твоя кровь 
пожелтеет, а ты умрёшь.